When you're not eating junk food you can actually eat a LOT of food for your calories. It's pretty awe-inspiring, actually. And it goes a long way toward illustrating why people are heavier today than they were 100 years ago!
1600-1800 sounds good. With your "indulgence" yesterday, you should be okay with staying more toward 1600 most days.
Veggies veggies veggies! But you already knew that.
I would suggest, instead of reduced FAT peanut butter, try reduced *sugar* peanut butter. The fats in peanut butter are the kinds your body needs. Skippy does a "natural" peanut butter with less sugar, look for that. Or just do natural peanut butter full stop--Laura Scudder's makes one (it's the kind you have to mix the oil back into).